Storable elevating platform

ABSTRACT

Storable elevating platform, particularly useful for attachment to trucks and other vehicles to raise and lower loads with respect to truck floor level, which platform can be tilted under the floor of the truck bed for storage when in nonuse and when the truck is traveling. A main support tube is rigidly secured transversely of the truck below the truck floor and forward of the edge thereof. Compression arms are pivoted to the platform and around the main support tube. Tension members having chain links, at least at the ends thereof, wrap around the main support tube and cam lobes on the platform. As the compression arms are raised, the tension members retain the platform substantially level. The platform is pivoted to the compression arms to permit the platform to be folded up and forward under the truck floor when not in use.

I United States Patent 1 [11] 3,737,055

Pettit [451 June 5, 1973 [54] STORABLE ELEVATING PLATFORM PrimaryExaminer-Robert J. Spar [76] lnventor: Charles A. Pettit, 2001 1 BernistAtt0mey Anen Dlcke Avenue, Torrance, Calif. 90503 [57] ABSTRACT [22]Flled: May 1971 Storable elevating platform, particularly useful for at-[211 App]. No.: 140,150 tachment to trucks and other vehicles to raiseand lower loads with respect to truck floor level, which. platform canbe tilted under the floor of the truck bed 'T 214/77 323 for storagewhen in nonuse and when the truck is [5 1 ll. Clt p tra eling A mainSupport tube is Secured an [58] Field of Search ..214/77 R, 77 P, 130,versely of the truck below the truck floor and forward ZM/DIG 1 BD ofthe edge thereof. Compression arms are pivoted to the platform andaround the main support tube. Ten- [56] References C'ted sion membershaving chain links, at least at the ends UNITED STATES ATENTS thereof,wrap around the main support tube and cam lobes on the platform. As thecompression arms are 2,469,321 5/1949 Woods... ..2l4/77 P raised, thetension members retain the platform sub- 3,545,79l 12/1970 Lugash....2l4/77 P tantially leveL The platform is pivoted to the com- PetalSen P pression arms to permit the platformsto be folded up 3,369,6782/1968 Robmso P and forward under the truck floor when not in use.2,719,637 10/1955 Wood 214/77 P 13 Claims, 8 Drawing Figures i/ lo l2 .64 r r A 38 36 90 as 36 9O 26 P 34 PATENTEDJUH 5 I975 SHEET1DF3' INVENTORCharles A. Petri'r,

BY AHen ADicke, Jr,

MiENTv STORABLE ELEVATING PLATFORM BACKGROUND This invention is directedto a storable elevating platform, particularly for use with trucks andis similar to tailgate lifts, power raising tailgates and other devicesfor raising and lowering loads with respect to the floor of a truck.

With increasing mechanization and higher labor costs, it became apparentin technological advance that mechanization for hoisting loads withrespect to truckbed level would be developed. Several types have beenmade available to truck users. One of the first concepts is to employ anormal truck tailgate, or a substitute therefor, as such a load-raisingand lowering device. The tailgate normally stood in the verticalposition at the rear of the truckbed and, from this application, theterm liftgate" has become fairly generic. The tailgate was swung fromits vertical position wherein it serves as a tailgate for the truckfloor, to a horizontal position substantially at the level of andsubstantially parallel to the floor. Thereupon, load could be placedfrom truck floor onto the liftgate. Lowering the gate would lower theload. Raising of a load was accomplished in the opposite manner.

A substantially parallelogramic arm structure was employed to maintainthe liftgate in fairly level position throughout its entire liftingmotion. The relationship of the parallelogramic arms permittedcantilevering of the liftgate and the strength of these parallelogramicarms generally determined the load limit of the gate.

Since it is inconvenient for the liftgate to extend out rearwardly fromthe truck floor during truck operation, and other nonuse of these priorliftgates, tilting of these gates from their lift position to a storageposition has been employed. One of the problems, of course, arises fromthe parallelogramic linkage which normally prevents dropping of theouter edge of the cantilevered tailgate. Special pivots and specialhinges permitted such folding action in prior structures.

Several prior storage positions have been employed. As previouslydiscussed, one of them included an upstanding platform which served asthe tailgate for the truck, during nonuse of the platform as a liftdevice. Other prior devices incorporated double folding into a positionbeneath the truck floor at the rear thereof, with double folding pivotsnecessitated by the liftgate hinge structure. All of these structureswere quite complex and do not fully satisfy the requirement that they beeconomic, sturdy, and reliable. In the past, whenever folding has beenemployed, special pivot structures have been necessary.

SUMMARY In order to aid in the understanding of this invention, it canbe stated in essentially summary form that it is directed to a storableelevating platform which is of particular use for raising and loweringloads with respect to the floor level of the truck. The elevatingplatform comprises a platform supported on compression arms and held upinto a substantially level position by means of tension members,including a flexible portion ofsaid tension members engaged around a camsurface on the lift platform, and engaged on the opposite end around amain support tube of the elevating platform mechanism.

Accordingly, it is an object of this invention to provide an elevatingplatform of economic and reliable construction which provides a longlife for lifting and lowering loads. It is a further object to providean elevating platform which is supported in cantilever fashion from aparallelogramic structure, including flexible tension members. It isstill another object to provide a stor- BRIEF DESCRIPTION OF THEDRAWINGS FIG. 1 is a perspective view of the storable elevating platformof this invention shown as applied to the rear end of a truck, and shownin the lowered position.

FIG. 2 is an enlarged side-elevational view thereof,

with parts broken away.

FIG. 3 is a view similar to FIG. 2, with further parts broken away, andshowing the elevating platform pivoted up to an intermediate positionfrom which it is raised to the storage position.

FIG. 4 is a view similar to FIG. 2, but showing the storable elevatingplatform in the storage position.

FIG. 5 is a further enlarged detail, taken partly in side elevation andpartly in section showing the latch structure which aids in retainingthe elevating platform in the storage position. 1

FIG. 6 is a view similar to FIG. 2, but showing the platform in theraised position.

FIG. 7 is a detail taken partly in side elevation and partly in verticalsection.

FIG. 8 is a view of the cylinder taken generally along the line 88 ofFIG. 7.

DESCRIPTION The storable elevating platform of this invention isparticularly useful with trucks, as described above. The preferredembodiment is described with respect to a truck, but it is clear thatthe elevating platform structure can be employed as a loading dock ofadjustable height, or other similar structure. Similarly, while theelevating platform is described as being attached to the rear of thetruck, this is the most convenient location, but it can be applied toother locations. Sometimes a use requirement suggests that a smallerplatform be attached to the side of the truck, and this employment iswithin the scope of use of the elevating platform of this invention.

To illustrate the manner of employment and attach-v ment of the storableelevating platform of this invention, it is shown as being associatedwith a truck 10, but

is subject to the other usages and attachments broadly described. Truck10 has a cargo box 12 which includes a floor 14. Floor 14, and theentire cargo box, is supported upon stringers 16. The truck has a frame18 upon which stringers 16 are mounted for support of the cargo box.

The storable elevating platform of this invention is generally indicatedat 20 in FIG. 1. It comprises a platform 22 and platform support means24. Brackets 26 and 28 are secured to and depend downwardly from thetruck frame 18, on opposite sides thereof, and toward the rear thereof.These brackets provide a substantial portion of the support of theplatform structure and, thus, are firmly secured and of good strength.Main support tube 30 passes through and is secured to the brackets 26and 28, and is positioned transversely of the truck. It extends in thewidthwise direction substantially equally to the width of platform 22.

The outer ends of tube 30 respectively carry supports 32 and 34 fromwhich uprights 36 extend. There are two uprights on each of the supports32 and 34, although only one may be used. The rearward upright serves asa dock bumper. The principal use of the up rights is for the support offloor extension 38 which is of the same approximate height as the truckfloor 14. The employment of two uprights 36 on each of the supports 32and 34 permits the installation of a ladder crosspiece, if such ishelpful in use of the platform. Floor extension 38 is secured to thestringers 16 under the cargo box of the truck and to such other partsofthe cargo box as may be convenient. Thus, the supports 32 and 34, aswell as uprights 36, serve for mutual support between the ends of mainsupport tube 30 and the floor extension on the cargo box.

FIGS. 1 and 7 show arms 40 and 42. These arms are the compression armsin a substantially parallelogramic linkage which supports the platform22 and permits its movement from its lowered to its raised position. Asillustrated in FIGS. 1 and 7, arms 40 and 42 embrace tube 30 by means ofan adjustable bearing structure wherein a bearing cap 44 is engagedaround main support tube 30 and is adjustably secured with respect tothe bearing half on the end of the compression arms by means of nuts andbolts. This provides for a large area of bearing, which reduces wear andreduces loading pressures, to result in a long bearing life. Suitablelubrication devices, such as grease fittings, are preferably employed.

Arms 40 and 42 pivot around the tube 30 on the bearings indicated, andare secured to each other by cross tubes 46 and 48, which maintain themin parallel positions. FIGS. 1, 7, and 8 illustrate cylinder 50 beingpivotally mounted under bridge 52 which is secured to main support tube30. Cylinder 50 has a piston rod 54 which can be extended from orwithdrawn into cylinder 50 by means of conventional hydraulic fluidunder pressure, controlled by conventional valves. The lower end ofpiston rod 54 carries a clevis 56. Pin 58 passes through clevis 56 andlug 60. Lug 60 is secured to cross tube 46. This provides a pivotalconnection between clevis 56 and lug 60. Furthermore, if adjustment ofextension length is desired, clevis 56 can be adjustably secured topiston rod 54, as by screwthreads, to provide suitable lengthadjustment. By this construction, it is clear that withdrawal of thepiston rod into cylinder 50 raises cross tube 46, while extension of therod from the cylinder lowers cross tube 46.

Since the cross tube is secured to both of the compression arms 40 and42, and these are pivoted at their upper ends on main support tube 30,it is clear that this 10) and the outermost supports are symmetricallyidentical. The nearest support in FIGS. 1, 2, 3, 4, and 6 of thedrawings can be considered one of the two side supports. It is indicatedby the numeral 64. These supports are preferably in channel form, inorder to give the requisite strength to the platform 22. Alternatively,flat plates on edge or box sections can serve as the support members.

Two additional supports are also illustrated, this being the minimumnumber of supports in the preferred embodiment. The center supports areidentical, and one is illustrated at 66 in FIG. 7. The central support66 illustrates its double wall character in FIG. 1. The forward end ofthe central support 66 carries an arcuate bearing slot 68. Compressionarm 42 extends between the two sides of central support 66 and cross pin70 extends through bearing slots 66 and is secured in arm 42. The crosspin is located at the bottom of bearing slot 68 in the position shown inFIGS. 1, 2, and 7 when the platform 22 is in the lowered position ofFIG. 1 or the raised position of FIG. 6, or any position intermediatetherebetween. It moves into the other end of this slot only when theplatform is moving from the lowered position of FIG. linto the storageposition of FIG. 4. Compression arms 40 and 42 serve as the one side ofa substantially parallelogramic structure. The arms 40 and 42 pivot onthe center line of main support tube 30 and the cross pins 70.

FIGS. 2 and 6 best illustrate the tension structure which maintains theplatform 22 in substantially level position between the lowered and theraised platform. The tension structure is comprised of tension members72 and 74. These are identical, and the one shown in the near side ofthe drawing is more conveniently explained. The forward end of tensionmember 72 includes a series of roller chain links 76. On their rearwardend, they are secured to bar 78. They wrap around main support tube 30,and are secured to bolt which passes through boss 82 secured to tube 30.The nut on bolt 80 beneath the boss permits adjustment of the overalleffective length of tension member 72. Chain 76 is preferably of thenature of a roller chain which presents flat plates lying edgewise onthe circumference of tube 30. The radius distance between the centerline of tube 30, on which the compression arms rotate, and the centerline of the chain 70 corresponds to one of the short arms of thesubstantially parallelogramic structure.

The lower end of bar 78 carries chain 84. Cam 86 is secured to the outerface of side support 64. Cam 86 is preferably of such thickness that theside plates of roller chain 84 embrace the cam, for sideways security.Cam 86 has an effective surface which is cylindrical. The radius fromthe center of the cam circle to the center line of chain 84 ispreferably substantially the same as the distance from the center oftube 30 to the center line of the chain wrapped therearound. By thisconstruction, if the center of cam 86 is located upon the axis of pin70, a perfect parallelogramic support results. However, it is desirablefor the platform to have its nose tipped down to the ground in thelowered position, as shown in FIG. 2, while the platform is level in theraised position, as shown in FIG. 6. This is accomplished by offsettingthe cam 86 so that the structure is not quite parallelogramic. As theplatform moves between the lowered and raised position, one of thechains wraps while the other one unwraps with respect to its curvedguide support. By operation of the cylinder 50, the platform moves fromthe lowered position of FIG. 2 to the raised position of FIG. 6. In theposition of FIG. 6, the platform top 62 is in line with floor extension38. The platform top is dimensioned so that they meet substantiallyedge-to-edge for convenient transfer of materials from the floorextension to the platform, and vice versa. By this means, materials aremoved substantially from ground level to the truck floor level, and viceversa. I

As previously discussed, the truck cannot proceed with the platform 22in the raised position as shown in FIG. 6. The platform must be put inan out-of-the-way position so that it is not a danger while driving. Itis desirable to place the platform 22 in such a position that the truckcan be backed up against an ordinary loading dock, without the need toemploy the platform 22. Thus, it is preferable that the platform not beraised to a vertical position, where it serves as a tailgate, but inaccordance with the preferred embodiment of this invention, that theplatform 22 be tilted under the truck body at the rear thereof.

Since tension member 72 is not the member of compressional strength,platform 22 can be manually pivoted by lifting its rearward edge upward.Furthermore, this manual lifting is aided by means of tension spring 88.The forward end of tension spring 88 is hooked on spring bracket 90.This bracket is secured to main support tube 30. The rearward end oftension spring 88 is engaged in strap 92, which in turn is adjustablysecured to bracket 94 secured to bar 78. Spring 88 maintains tension onchain 84, and the torque resulting from this tension force aids inlifting the rearward edge of platform 22. As the platform 22 is manuallyraised to the vertical position, pin 96 is positioned to engage thechain 84 and prevent the chain from following the full radius of itsaction. Thus, the effectiveness of the spring to produce acounterclockwise torque is reduced as the platform reaches its verticalposition. During this raising, the pin 70 moves to the opposite end ofarcuate slot 68, so that the pivot point during the manual liftingprocedure is at the upper end of slot 68.

The platform 22 is swung upward until it passes between the uprights 36,and with further inward tilting, it engages guides 98. The firstengagement with the guides 98 is shown in FIG. 3. From this position,cylinder 50 is powered to raise arms 40 and 42. As the arms raise, theplatform 22 tilts down over the guides 98 until the arms 40 and 42engage on the now downwardly directed platform top 62. From thisposition, the arms move upward to the fully raised position of FIG. 4.During this entire motion, from the first manual lifting of the rearwardedge of platform 22, chain 76 has been slack. However, spring 88 keepsthe tension member 72 under control, despite the slackness of the chain76, which is illustrated in FIG. 4.

A conventional control handle 100 is mounted to be available to theoperator of platform 22. Preferably, a handle is available on each sideof the truck, beneath floor extension 38. Cross shaft 102 is connectedbetween these handles, and is connected to operate the hydraulic controlvalve which drives cylinder 50, in conventional manner. As previouslystated, hydraulic fluid under pressure is received by the valve and isdirooted to the cylinder by conventional means.

As a protective device, latch 104 is pivotally attached to the undersideof floor extension 38. It is shown under the center of floor extension38 in FIG. I and in detail in FIG. 5. It is connected by bellcrank 106and link 108 I -damage. The structure is such that, when the handle ismoved to a position which calls for lowering the platform 22 out of itsstowed position, the hook disengages. Upon such lowering, as the arms 44and 42 pass below guides 98, the platform is swung partway forward, tothe position of FIG. 3. From this position, it is manually swung outwardto the horizontal, lowered position of FIG. 2, by use of the handle 114on either side of platform 22.

When the platform is in the stowed position, there is clearance belowthe floor extension and above the now raised rear edge of the platform.This space permits mounting of lights at the rear of the truck,underneath the floor extension, which lights are visible to the rear.All legally-required rear facing lights can be placed at the lower rearof the truck. In this location, they are visible with the platform inthe stowed position and are out of the way of platform or cargo box reardoor movement. Additionally, they are protected by being positionedunder the floor extension.

The guide arms about which the platform swings as it moves into and outof stowed position define a zone in which the platform cannot move.Thus, a trailer hitch can be connected to the truck frame or the mainsupport tube and extend into a central position approximately belowthese guide arms. In this position, the trailer hitch does not interferewith platform motion, either in the elevating and descending mode or asthe platform is moved into stowage position.

By this means, a fully-adjustable, economic, but fully secure storableelevating platform is accomplished. This invention having been describedin its preferred embodiment, it is clear that it is susceptible tonumerous modifications and embodiments within the ability of thoseskilled in the art and without the exercise of the inventive faculty.Accordingly, the scope of this invention is defined by the scope of thefollowing claims.

What is claimed is:

1. An elevating platform for moving from a lowered position to a raisedposition, said platform comprising:

a fixed non-rotative main support, a curved exterior surface on saidsupport, said curved exterior surface having an axis;

at least one support arm having an inner end pivotally mounted upon saidfixed main support away from the axis of its curved surface and havingan outer end;

a platform pivotally mounted on the outer end of said support arm, acurved surface on said platform;

a flexible tension member engaged around said curved surface on saidsupport and around said curved surface on said platform so that tensionin said flexible tension member controls the level of said platform assaid support arm pivots on said support.

2. An elevating platform for moving from a lowered position to a raisedposition, said platform comprising:

a fixed non-rotative main support, a curved substantially cylindricalexterior surface on said support, said curved substantially cylindricalexternal surface having an axis;

at least one support arm having an inner end pivotally mounted upon saidsubstantially cylindrical surface of said fixed main support and saidsupport arm pivots substantially on the cylindrical axis of said mainsupport, said support arm having an outer end; a platform pivotallymounted upon a platform pivot axis on the outer end of said support arm,a curved surface on said platform, said curved surface having nosubstantial axis of curvature on the pivot axis ofsaid platform on theouter end of said support arm; and

a flexible tension member engaging around said curved surface on saidsupport and around said curved surface on said platform so that tensionin said flexible tension member controls the level of said platform assaid support arm pivots on said support.

3. The elevating platform of claim 2 wherein said main support is a mainsupport tube and wherein there are first and second support arms, saidsupport arms being engaged around and bearing on the outside of saidmain support tube at the inner ends of said support arms.

4. The elevating platform of claim 3 wherein the exterior surface ofsaid main support tube is the curved surface upon which said flexibletension member engages so that the center of curvature thereof lies onthe same axis as the pivot axis of said arms on said main support tube.

5. The elevating platform of claim 4 wherein said curved surface on saidplatform is a cylindrical surface, the center of which is spaced awayfrom the pivot axis of said platform on the ends of said support arm.

6. An elevating platform for moving from a lowered position to a raisedposition, said platform comprising:

a fixed non-rotative tubular main support having a curved substantiallycylindrical exterior surface, said curved exterior surface having anaxis;

first and second support arms each having an inner end, said inner endsof said support arms being engaged around and bearing on the exteriorcylindrical surface of main support tube at the inner ends of saidsupport arms;

a platform pivotally mounted on the outer end of said support arm topivot on said support arms on a platform pivot axis an arcuate slot insaid platform and a pivot pin on the outer end of said support armengaged in said arcuate slot to define the pivot axis of said platformon said support arms, a curved surface on said platform, said curvedsurface having at least a principal axis of curvature, said principalaxis of curvature being spaced away from the pivot axis of saidplatform; and

a flexible tension member engaged around said cylindrical exteriorsurface of said main support tube and around said curved surface on saidplatform so that tension in said flexible tension member controls thelevel of said platform as said support arms pivot on said main supporttube.

7. The elevating platform of claim 6 wherein guide means is positionedon said platform adjacent said flexible tension member adjacent its wraparound said curved surface on said platform so that said tension memberis restrained adjacent said curved surface when said platform is pivotedon the end of said arm.

8. An elevating platform for moving from a lowered position to a raisedposition, said platform comprising:

a fixed non-rotative main support, a curved exterior surface on saidmain support, said curved exterior surface having an axis;

at least one support arm having an inner end, said inner end beingengaged upon said curved exterior surface of said main support and beingpivotally mounted thereon, said support arm having an outer end;

a platform pivotally mounted on the outer end of said support arm, acurved surface on said platform;

a flexible tension member engaged around said curved surface on saidsupport and around said curved surface on said platform;

guide means positioned on said platform adjacent said flexible tensionmember adjacent its wrap around said curved surface on said platform sothat said tension member .is restrained adjacent said curved surfacewhen said platform is pivoted on the end of said support arm, thetension in said flexible tension member controlling the level of saidplatform as said support arm pivots on said support.

9. The elevating platform of claim 8 wherein one end of said flexiblemember is adjustable with respect to its curved surface so that thelevel of said platform can be adjusted.

10. The elevating platform of claim 8 wherein tension spring means isconnected between said flexible member and said main support to holdsaid tension member taut with respect to said platform when saidplatform is pivoted up on the end of said support.

11. The elevating platform of claim 10 wherein a floor is positionedeven with the raised position of said platform, and said support arm andsaid platform are shaped so that said platform is movable into a storageposition below said floor, and when in said storage position, saidplatform is spaced below said floor.

12. The elevating platform of claim 1 wherein a floor is positioned evenwith the raised position of said platform, and said support arm and saidplatform are shaped so that said platform is movable into a storageposition below said floor, and when in said storage position, saidplatform is spaced below said floor. v

13. The elevating platform of claim 1 wherein a floor is positionedsubstantially even with the raised position of said platform, supportssecured to the said fixed main support and extending beneath said floor,uprights extending from said supports to said floor, said supports andsaid uprights being positioned so that's aid support arms, said platformand said flexible tension member pass between said supports and saiduprights as said platform moves from its lower position to its raisedposition.

1. An elevating platform for moving from a lowered position to a raisedposition, said platform comprising: a fixed non-rotative main support, acurved exterior surface on said support, said curved exterior surfacehaving an axis; at least one support arm having an inner end pivotallymounted upon said fixed main support away from the axis of its curvedsurface and having an outer end; a platform pivotally mounted on theouter end of said support arm, a curved surface on said platform; aflexible tension member engaged around said curved surface on saidsupport and around said curved surface on said platform so that tensionin said flexible tension member controls the level of said platform assaid support arm pivots on said support.
 2. An elevating platform formoving from a lowered position to a raised position, said platformcomprising: a fixed non-rotative main support, a curved substantiallycylindrical exterior surface on said support, said curved substantiallycylindrical external surface having an axis; at least one support armhaving an inner end pivotally mounted upon said substantiallycylindrical surface of said fixed main support and said support armpivots substantially on the cylindrical axis of said main support, saidsupport arm having an outer end; a platform pivotally mounted upon aplatform pivot axis on the outer end of said support arm, a curvedsurface on said platform, said curved surface having no substantial axisof curvature on the pivot axis of said platform on the outer end of saidsupport arm; and a flexible tension member engaging around said curvedsurface on said support and around said curved surface on said platformso that tension in said flexible tension member controls the level ofsaid platform as said support arm pivots on said support.
 3. Theelevating platform of claim 2 wherein said main support is a mainsupport tube and wherein there are first and second support arms, saidsupport arms being engaged around and bearing on the outside of saidmain support tube at the inner ends of said support arms.
 4. Theelevating platform of claim 3 wherein the exterior surface of said mainsupport tube is the curved surface upon which said flexible tensionmember engages so that the center of curvature thereof lies on the sameaxis as the pivot axis of said arms on said main support tube.
 5. Theelevating platform of claim 4 wherein said curved surface on saidplatform is a cylindrical surface, the center of which is spaced awayfrom the pivot axis of said platform on the ends of said support arm. 6.An elevating platform for moving from a lowered position to a raisedposition, said platform comprising: a fixed non-rotative tubular mainsupport having a curved substantially cylindrical exterior surface, saidcurved exterior surface having an axis; first and second suPport armseach having an inner end, said inner ends of said support arms beingengaged around and bearing on the exterior cylindrical surface of mainsupport tube at the inner ends of said support arms; a platformpivotally mounted on the outer end of said support arm to pivot on saidsupport arms on a platform pivot axis an arcuate slot in said platformand a pivot pin on the outer end of said support arm engaged in saidarcuate slot to define the pivot axis of said platform on said supportarms, a curved surface on said platform, said curved surface having atleast a principal axis of curvature, said principal axis of curvaturebeing spaced away from the pivot axis of said platform; and a flexibletension member engaged around said cylindrical exterior surface of saidmain support tube and around said curved surface on said platform sothat tension in said flexible tension member controls the level of saidplatform as said support arms pivot on said main support tube.
 7. Theelevating platform of claim 6 wherein guide means is positioned on saidplatform adjacent said flexible tension member adjacent its wrap aroundsaid curved surface on said platform so that said tension member isrestrained adjacent said curved surface when said platform is pivoted onthe end of said arm.
 8. An elevating platform for moving from a loweredposition to a raised position, said platform comprising: a fixednon-rotative main support, a curved exterior surface on said mainsupport, said curved exterior surface having an axis; at least onesupport arm having an inner end, said inner end being engaged upon saidcurved exterior surface of said main support and being pivotally mountedthereon, said support arm having an outer end; a platform pivotallymounted on the outer end of said support arm, a curved surface on saidplatform; a flexible tension member engaged around said curved surfaceon said support and around said curved surface on said platform; guidemeans positioned on said platform adjacent said flexible tension memberadjacent its wrap around said curved surface on said platform so thatsaid tension member is restrained adjacent said curved surface when saidplatform is pivoted on the end of said support arm, the tension in saidflexible tension member controlling the level of said platform as saidsupport arm pivots on said support.
 9. The elevating platform of claim 8wherein one end of said flexible member is adjustable with respect toits curved surface so that the level of said platform can be adjusted.10. The elevating platform of claim 8 wherein tension spring means isconnected between said flexible member and said main support to holdsaid tension member taut with respect to said platform when saidplatform is pivoted up on the end of said support.
 11. The elevatingplatform of claim 10 wherein a floor is positioned even with the raisedposition of said platform, and said support arm and said platform areshaped so that said platform is movable into a storage position belowsaid floor, and when in said storage position, said platform is spacedbelow said floor.
 12. The elevating platform of claim 1 wherein a flooris positioned even with the raised position of said platform, and saidsupport arm and said platform are shaped so that said platform ismovable into a storage position below said floor, and when in saidstorage position, said platform is spaced below said floor.
 13. Theelevating platform of claim 1 wherein a floor is positionedsubstantially even with the raised position of said platform, supportssecured to the said fixed main support and extending beneath said floor,uprights extending from said supports to said floor, said supports andsaid uprights being positioned so that said support arms, said platformand said flexible tension member pass between said supports and saiduprights as said platform moves from its lower position to its raisedposition.